For discussion of all the other girl+mecha lines that have cropped up since Shinki began: Frame Arms: Girls, Megami Device, Armor Girls Project, Desktop Army, etc. This includes kinda-sortas like Daibadi's Polynian and things like Strike Witches and Fumikane's original Mecha Musume.

It's very charitable of koto to call Byakko (not 'Hyakko'; where did that come from, out of curiosity?) a Frame Arms kit, actually. It uses the architect in a very... sparing manner. So it's not too weird for the FA:G version to do the same.

That said, aside from the early fumikane designs being INCREDIBLY samey, koto doesn't seem to intend for the girls to be the same playpattern as the normal frame arms themselves.

You're wrong, this isn't part of F.A.G. nor any Kotobukiya product. I've seen them now in Wonfes cover by Dengeki hobby-http://hobby.dengeki.com/event/420524/ , as far as I can tell they belong to Embrace Japan company? They're going to be released in 2018. That's why it's important that you woul add the source (link) from where you took thing and by the way, give t the credit it desrves.